http://answers.yahoo.com/question/index?qid=20061113221628AAxlNn5Also known as "Titin"
I find that one isn't hard to pronounce but takes a while...
This one is also hard.
methionylglutaminylarginyltyrosylglutamylserylleuc ylphenylalanylalanylglutaminylleucyll
ysylglutamylarginyllysylglutamylglycylalanylphenyl alanylvalylprolylphenylalanylvalylthre
onylleucylglycylaspartylprolylglycylisoleucylgluta mylglutaminylserylleucyllysylisoleucylas
partylthreonylleucylisoleucylglutamylalanylglycyla lanylaspartylalanylleucylglutamylleuc
ylglycylisoleucylprolylphenylalanylserylaspartylpr olylleucylalanylaspartylglycylprolylthreo
nylisoleucylglutaminylaspfraginylalanylthreonylleu cylarginylalanylphenylalanylalanylala
nylglycylvalylthreonylprolylalanylglutaminylcystei nylphenylalanylglutamylmethionylleuc
ylalanylleucylisoleucylarginylglutaminyllysylhisti dylprolylthreonylisoleucylprolylisoleucylg
lycylleucylleucylmethionyltyrosylalanylasparaginyl leucylvalylphenylalanylasparaginyllysy
lglycylisoleucylaspartylglutamylphenylalanyltyrosy lalanylglutaminylcysteinylglutamyllysyl
valylglycylvalylaspartylserylvalylleucylvalylalany laspartylvalylprolylvalylglutaminylglutam
ylserylalanylprolylphenylalanylarginylglutaminylal anylalanylleucylarginylhistidylasparagi
nylvalylalanylprolylisoleucylphenylalanylisoleucyl cysteinylprolylprolylaspartylalanylaspar
tylaspartylaspartylleucylleucylarginylglutaminylis oleucylalanylseryltyrosylglycylarginylglyc
yltyrosylthreonyltyrosylleucylleucylserylarginylal anylglycylvalylthreonylglycylalanylglutam
ylasparaginylarginylalanylalanylleucylprolylleucyl asparaginylhistidylleucylvalylalanyllysyl
leucyllysylglutamyltyrosylasparaginylalanylalanylp rolylprolylleucylglutaminylglycylphenyl
alanylglycylisoleucylserylalanylprolylaspartylglut aminylvalyllysylalanylalanylisoleucylaspa
rtylalanylglycylalanylalanylglycylalanylisoleucyls erylglycylserylalanylisoleucylvalyllysylisol
eucylisoleucylglutamylglutaminylhistidylasparaginy lisoleucylglutamylprolylglutamyllysylm
ethionylleucylalanylalanylleucyllysylvalylphenylal anylvalylglutaminylprolylmethionyllysyl
alanylalanylthreonylarginylserine.
Now say it ten times fast...

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